When drilling oil or gas wells, a well may pass through one or more formations that contain oil or gas deposits. When the well is cased in, the formations are then sealed in and can only be accessed if the well casing is perforated to allow substances within the formation to be withdrawn. To perforate a well casing, a perforation device containing explosives is placed down the well to a location adjacent to the formation. The device is detonated resulting in a perforation in the well casing to allow access to the substances. It is known that devices that emit RF signals, such as radios, pagers, cellular phones, GPS modems and the like can accidentally cause the perforation device to detonate prematurely. This can damage the well casing and impair the ability to withdraw substances from down-hole formations as the well casing will not be perforated at the correct location. This is also a safety concern as perforation devices may be prematurely detonated prior to being inserted into the well causing a significant hazard to personnel in proximity to the perforation operations. Electronic devices that emit RF signals are also a hazard in the mining especially where explosives are used in blasting operations to collect ore.
In respect of vehicles equipped with GPS modems, some currently available units have the ability to manually disable the modem so as to terminate RF transmissions but this feature usually results in the total shutdown of the modem. Fleet vehicles equipped with GPS modems are often configured to monitor operational parameters of the vehicle that are transmitted to the fleet headquarters using the GPS modem as a method of tracking the vehicle and its usage. This information can include when the vehicle is operating, the location of the vehicle, when the vehicle exceeds posted speed limits among other operational parameters pertinent to the control and management of the fleet vehicle. The known manual shutdown function usually shuts down the ability of the GPS modem to monitor these operational parameters thereby negating the ability to monitor and record vehicle parameters when the modem is disabled.
It is, therefore, desirable to provide an apparatus and method to manually disable RF signal transmissions from a GPS modem that still allows the GPS modem to collect vehicle operational parameters that can be transmitted once the GPS modem is re-enabled after travelling a safe distance from the perforation operations.